A cable television distribution system generally transmits both a line power voltage and high frequency television signals through the same coaxial cable line. The line power voltage, which can be a square wave direct current voltage, is utilized to provide power to the line amplifiers, which are located at intervals along a cable line, for maintaining the strength of the high frequency signals being transmitted through the cable line.
A take-off connection for the high frequency signals can be accomplished through the utilization of a directional coupler module or a tap module. The primary purpose of a directional coupler module or a tap module is to provide a take off of the high frequency signals. A commonly employed directional coupler module, which can be viewed as a Y connection for the radio frequency television signals, has a pair of inlet ports, a pair of outlet ports, a pair of drop/tap ports, and a pair of dummy ports. An inlet cable can be connected to one of the pair of inlet ports, with the other inlet port having a removable cap so as to serve as an access port for the installation of the inlet cable in the first inlet port. Similarly, an outlet cable can be connected to one of the pair of outlet ports with the other outlet port having a removable cap so as to serve as an access port for the installation of the outlet cable in the first outlet port. Each of the dummy ports is provided with a removable cap. A secondary output cable can be connected to one of the pair of drop/tap ports, with the other of the pair of drop/tap ports serving as an access port for the installation of the secondary output cable in the first drop/tap port. A commonly employed tap module has a pair of inlet ports, a pair of outlet ports, and one or more customer drop ports. One of the inlet ports and one of the outlet ports serve as access ports for the installation of the inlet cable and the outlet cable in the other inlet port and the other outlet port, respectively. Basically, the tap modules are passive devices for eliminating the line power voltage from the signals being applied to the customer drop ports.
However, recent developments in cable television distribution systems provide for equipment, requiring a power supply, to be installed at the tap module, such as scrambling/unscrambling devices and devices for preventing unauthorized transmission of the radio frequency television signals. Such additional devices need to be able to utilize the line power voltage that is carried by the cable, without adversely impacting the radio frequency television signals.